High7.5Red Hat & Ubuntu Linux
Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149
CVE-2026-4721 Published Mar 24, 2026
CVE-2026-4721
Affected products & platforms
Red Hat & Ubuntu LinuxUnclassified
Summary
Memory safety bugs fixed in Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Red Hat rates this important (CVSS 7.5). Weakness: CWE-825. Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:6917 — update the affected packages (`sudo dnf update`).
Affected versions
- firefox-0:140.9.0-1.el8_10
- thunderbird-0:140.9.0-1.el8_10
- firefox-0:140.9.0-1.el8_4
- firefox-0:140.9.0-1.el9_2
- firefox-0:140.9.0-1.el8_2
- firefox-0:140.9.0-1.el9_0
- firefox-0:140.9.0-1.el7_9
- firefox-0:140.9.0-1.el8_8
- firefox-0:140.9.0-1.el9_7
- firefox-0:140.9.0-1.el9_6
- firefox-0:140.9.0-1.el8_6
- firefox-0:140.9.0-1.el9_4
Official advisory · high-confidence parse· fetched 5 hours ago·verify at source
Fixed versions
- RHSA-2026:6917
Official advisory · high-confidence parse· fetched 5 hours ago·verify at source
Mitigation checklist
Recommended fix / mitigation
- Update the affected package(s) to the fixed version shipped in RHSA-2026:6917 (`sudo dnf update` / `yum update`).
Official advisory · high-confidence parse· fetched 5 hours ago·verify at source
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